How to Test Your Air Tanks

How to Drain / Test Your Air Tanks

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Overview:
The following information was taken from a Spartan chassis service seminar as is specific to the Spartan chassis.

Modern coaches are equipped with an air dryer that provides clean, dry air to the system so you may feel the need for manually draining the air tanks is unnecessary but that is not the case.

The main purpose in draining air tanks is not to remove the moisture from the system, but to test that the air system is functioning properly.  If the air drier is doing it's job there should be very little, if any, moisture expelled from the tanks when the manual tank drains are opened. If you do see excessive moisture coming out it is time to service the air drier.

The normal procedure is for you to  pull the tank drain lanyards for a second, then release them. Any moisture within the tank that had settled to the bottom would be expelled.  The Spartan procedure allows us to goes a step farther and test the check valves within / between the air tanks.

The Anthem and Conerstone lanyards are located in the passenger front wheel well, the Aspire has two in front and the third is at the rear right side between the rear wheels.

Test Procedure:

• With engine off, make sure both air gauges read 70 PSI or less.  If they read higher, lightly pump the brake pedal several times until the dash air pressure gauges read 70 PSI or less.
• Start the engine and run it until the Air Drier purge is heard in the rear of the vehicle.
• Turn the engine OFF, but leave the ignition switch ON so that the gauges are available for reading the air pressure.  Do not start the engine.
• Never reach your arm into a wheel well or crawl beneath the coach when you drain the air tanks. You can safely reach the lanyards using your awning hook.
• Pull the SILVER / CLEAR lanyard (wet tank) for several seconds. There should be no significant moisture expelled. Release the lanyard and go into the coach and check the gauges. They should not have changed. This will ensure that the check valve between the primary and wet tank is functioning properly.
• Pull the GREEN lanyard (primary tank - rear air) for several seconds There should be no significant moisture expelled. Release the lanyard and check the air pressure gauges once again. The rear gauge (primary system) should be reading lower and the front gauge (secondary system) should not have changed. This will ensure that the check valve between the primary and secondary tank is functioning properly.
• Pull the RED lanyard (secondary tank - front air) for several seconds. There should be no significant moisture. Release the lanyard and check the air pressure gauges once again. The front gauge should drop while the first remaining where it was. 
• Make sure that all of the drain valves are closed and restart the engine. Run at a fast idle until the air dryer purges. The system should now be ready for operation and both gauges should read somewhere around 110-120 PSI